It has been reported that the glucopyranosyloxypyrazole derivatives represented by the above general formula (A) are useful as agents for the prevention or treatment of a disease associated with hyperglycemia such as diabetes, diabetic complications, obesity or the like (for example, see Patent References 1 to 13).
Previously, as the method for preparing the glucopyranosyloxypyrazole derivatives represented by the above general formula (A), glycosylation using a benzylpyrazole derivative represented by the general formula:
wherein R66 is a C1-6 alkyl group, and R1 and R2 have the same meanings as defined above, and a hydroxy-protected α-D-glucopyranosylhalogen derivative in the presence of silver carbonate or silver oxide containing silver that is a heavy metal has been reported (for example, see Patent References 1 to 6).
However, when the glycosylation is carried out for a hydroxy-protected α-D-glucopyranosylbromide using the pyrazole derivative represented by the above general formula (II) wherein R66 is a lower alkyl group under reported condition, side reactions that the pyrazole derivative represented by the above general formula (II) used in the reaction reacts with each other or that a nitrogen atom on the pyrazole ring is glycosylated occur, and the problems could not be avoided. And a problem that a special purification process to remove those by-products was needed existed. Furthermore, conditions to use a strong base or a reagent that contains silver that is the heavy metal was examined to suppress the side reaction. However, when the heavy metal is used for the manufacturing process of a medicine, a special purification process is necessary so that the heavy metal used does not remain in the medicine, and various analyze characteristics to be inspected to confirm whether the heavy metal remains in the medicine have to be conducted, therefore, there was a problem that a number of complex working increased. Heretofore, it is reported that reaction time becomes long if silver is not used, and for example, it requires several days to glycosylate, though other glycosylations without the use of the reagent that contains silver are examined to solve these problems (see Patent Reference 6). On the other hand, though a method by adding a phase-transfer catalyst to shorten the time of the glycosylation is also examined, so this time, various problems such as a problem that large excess of a sugar donor is needed, a problem that reactive yield is not constant, and a problem that conduct on an industrial scale is difficult are caused.
On the other hand, in Patent Reference 14, a method for obtaining a 5-thio-D-glucopyranoside derivative represented by the general formula:
by subjecting a pyrazole derivative represented by the general formula:
and 2,3,4,6-tetra-O-acetyl-5-thio-D-glucose represented by a formula:
to Mitsunobu reaction that uses triphenylphosphine and diisopropylazodicarboxylate is described. However, this reaction is different from the present invention because it is a different product (a 5-thio-D-glucopyranoside derivative) by a different method for preparing (Mitsunobu reaction) by the use of a different substrate 2,3,4,6-tetra-O-acetyl-5-thio-D-glucose. Moreover, in the above Patent Reference 14, it is not described that this reaction is applicable to manufacturing of an α-D-glucopyranosylhalogen derivative. And because the α/β selectivity of the product is not excellent, Mitsunobu reaction described in the above Patent Reference 14 has a problem that another process to remove the product of unnecessary configuration is needed, and unnecessary product should be disposed in economical respect. And Mitsunobu reaction has a problem of generating triphenylphosphine oxide difficult to remove as a by-product.
As mentioned above, the methods ever reported are not always satisfactory, and the development of a easier and more efficient process of manufacturing has been desired.    Patent Reference 1: International Publication WO02/053573 pamphlet;    Patent Reference 2: International Publication WO01/16147 pamphlet;    Patent Reference 3: International Publication WO02/068439 pamphlet;    Patent Reference 4: International Publication WO02/36602 pamphlet;    Patent Reference 5: International Publication WO02/020737 pamphlet;    Patent Reference 6: International Publication WO02/088157 pamphlet;    Patent Reference 7: Japanese Patent Publication 2003-012686;    Patent Reference 8: International Publication WO2005/021566 pamphlet;    Patent Reference 9: Japanese Patent Publication 2004-137245;    Patent Reference 10: International Publication WO02/098893 pamphlet;    Patent Reference 11: International Publication WO2004/014932 pamphlet;    Patent Reference 12: International Publication WO2004/018491 pamphlet;    Patent Reference 13: International Publication WO2004/019958 pamphlet;    Patent Reference 14: International Publication WO2004/089967 pamphlet.